Apparatus for drying workpieces in bulk

ABSTRACT

An apparatus for drying workpieces in bulk while disposed within an elongated foraminous treating barrel formed with an opening extending longitudinally of the ends thereof. The apparatus includes a framework which defines an upwardly open threedimensional chamber into which the treating barrel is adapted to be lowered and in which it is oscillated such that the opening therein is alternatively aligned with a pair of discharge ports located in opposed sides of the chamber through which heated air is discharged against the periphery of the barrel and through the opening against the workpieces therein. An exhaust port is provided in the lower region of the chamber for continuously withdrawing moisture-laden air from the chamber and from the interior of the barrel which is recirculated in admixture with make-up air by means of a blower through a heat exchanger and thereafter is discharged through the discharge ports in the chamber.

United States Patent [191 .lessup et a1.

[ APPARATUS FOR DRYING WORKPIECES 1N BULK inventors: Richard J. Jessup,Bloomfield Hills; Andrew N. Sulfaro, Sterling Heights, both of Mich.

[73] Assignee: Oxy Metal Finishing Corporation,

Warren, Mich.

[22] Filed: July 17, 1972 [21] Appl. No.: 272,646

52 us. C1 214/131, 34/133, 34/13'9,

' 34/135 51 lnt.Cl. F26b25/06 531 FieldofSearch ..34/131,102,-10s,

[56] References Cited UNITED STATES PATENTS 3,718,485 2/1973 Lankford34/109 2,503,448 4/1950 Morris 34/139 3,190,011 6/1965 Shields 34/1332,522,448 9/1950 Husk et al.... 34/131 3,061,942 Scofield 34/133 PrimaryExaminerJohn J. Camby Assistant Examiner1-1enry C. Yuen Attorney].' KingHarness et al.

[57] ABSTRACT An apparatus for drying workpieces in bulk while disposedwithin an elongated foraminous treating barrel formed with an openingextending longitudinally of the ends thereof. The apparatus includes aframework which defines an upwardly open three-dimensional chamber intowhich the treating barrel is adapted to ,be lowered and in which it isoscillated such that the opening therein is alternatively aligned with apairof 10 Claims, 6 Drawing Figures APPARATUS FOR DRYING WORKPIECES INBULK BACKGROUND OF THE INVENTION The present invention broadly relatesto apparatus for plating or chemically treating workpieces in bulk.workpieces of the type adaptable to bulk treatment are generally toosmall to be individually handled or placed on racks and are, therefore,most conveniently handled by placing them in foraminous treating barrelsin which the workpieces are tumbled in response to a rotation oroscillation of the barrelwhile immersed in the various chemical treatingsolutions.

The treating barrels comprise a pair of end panels or members and aforaminous or perforate body panel extending between the end members anddefining in combination an internal, substantially cylindrically shapedzone in which the workpieces are disposed. The perforate body panel maycomprise a series of flat panels whereby the treating zone is of apolygonal cross'sectional configuration, such as hexagonal, forexainple, or alternatively, may be of a circular cross sectionalconfiguration including one or a plurality of tumbling ribs therealongto impart a cascading action to the workpieces in response to a rotationor oscillation of the barre.

In the treatment of extremely small workpieces, such as washers, screws,bolts, springs, metallic stampings, electrical contacts and the like, itis necessary during the processing of workpieces, and more usually atthe conclusion of a treating cycle, to effect a substantially completedrying of the workpieces to remove the residual treating solution on thesurfaces thereof. The en trapment of treating solutions within the massof workpieces and the capillary attraction of such solutions within theworkpieces themselves,.as well as in the apertures of the perforate bodypanels of the treating barrel, has provided a continuing problem .ineffecting a rapid and thorough drying of such bulk quantities ofworkpieces. In many instances, the workpieces at the conclusion of oneprocessing cycle are dumped from the treating barrel into a separatedrying apparatus,

whereafter they are reloaded in the treating barrel forfurtherprocessing. Alternatively, theparts are retained in the originaltreating barrel and are subjected to arelatively time-consuming tumblingaction in the presence of heated air in an attempt to effect anevaporation and substantially complete drying of the workpieces. In someinstances, the excessive tumbling to which the workpieces are subjectedduring the drying cycle has been detrimental to the surface treatmentspreviously applied, requiring further precautionary measures to assuresatisfactory product quality.

The problems and disadvantages of prior art drying apparatuses areovercome in accordance with the bulk dryer comprising the presentinvention, whereby the workpieces can be conveniently retained in theorginal treating barrel and are substantially completely dried withinrelatively shortperiods of time while being subjected to only a minimaloscillation or tumbling during the drying cycle.

SUMMARY OF THE INVENTION can also be satisfactorily utilized ineffecting a treatment of such workpieces in bulk employing a variety ofgases and/or vapors as may be desired. The apparatus is eminentlyadapted for use in completely automatic processing systems in which workcarriers, each including an elongated foraminous treating barrel, areautomatically transported and successively lowered into position withinan upwardly opening three-dimensional chamber defined by the frameworkof the dryer apparatus. The side walls of the chamber are formed with apair of opposed discharge ports extending longitudinally thereof inaddition to an outlet port formed in the lower portion of the chamber.Appropriate support means are provided on the framework for supportingthe barrel in alignment relative to the chamber such that an elongatedopening in the barrel can be alternatively disposed in communicativealignment with one of the discharge ports for receiving a gas dischargedtherefrom which impinges against the workpieces contained within theinterior of the barrel. The gas discharged from the other discharge portimpinges against the periphery of the barrel and serves to dislodge anyentrapped treating liquids within the perforations or other openings ofthe body panels.

In a normal drying operation in which the gas is air, a circulation ofthe heated air through the interior of the barrel is facilitated by thecontinuous withdrawal of air from the chamber through the outlet portwhich is connected to an exhaust port disposed in communication with thesuction side of a blower. A plenum is connected to the pressure side ofthe blower, which in turn is connected inseries with supply ductsconnected to the discharge ports, whereby a continuous recirculation ofa portion of the air is effected in admixture with an appropriatequantity of make-up air to maintain the moisture level thereof below thesaturation point.

Further advantages and benefits of the present invention will becomeapparent upon a reading of the description of the preferred embodimentstaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a schematic plan view ofatypical processing arrangement including the treating apparatuscomprising the present invention located at one work station'th'ereof;

FIG. 2 is a perspective view, with portions thereof broken away forclarity, of a typical work carrier incorporating an elongated foraminoustreating barrel rotatably supported thereon;

FIG. 3 isa plan view of the dryer apparatus constructed in accordancewith the preferred embodi- DESCRIPTION OF THE PREFERRED EMBODIMENTSReferring now in detail to the drawings, and as may be best seen in FIG.ll, an arrangement is illustrated typical of those to which theapparatus comprising the present invention is applicable in which bulkquantities of small workpieces, such as nails, screws, bolts, washers,small metal stampings or the like, are adapted to be transported withina foraminous or porous treating barrel through a plurality of liquidtreating stations to effect a cleaning and electroplating of thesurfaces thereof. In accordance with the illustrated arrangement, workcarriers, such as a work carrier 14 as shown in FIG. 2, are loaded andunloaded with workpieces at the input station indicated at 1, whereafterthe loaded work carriers are automatically transferred through asequentially phased process cycle typically comprising the followingsteps: a soak-cleaning operation at station 2; an electro-cleaningoperation at station 3; a cold water rinsing step at station 4; an acidtreatment at station 5; a cold water rinse at station 6; a second coldwater rinse at station 7; an electroplating operation at amultiple-station treating tank indicated at 8; a cold water rinse atstation 9; a second cold water rinse of shorter duration at station 10;a chromate treatment at station 11; a hot or cold water rinse at station12; and, finally, a drying operation employing the apparatus of thepresent invention at station 13. Thereafter, the work carriers are againtransferred to the load and unload station 1, at which the processedworkpieces are removed and a fresh quantity of workpieces are loadedinto the treating barrels for a repetition of the foregoing cycle. Itwill be understood that the dryer apparatus at station 13 can beduplicated at one or more additional stations in order to provide therequisite drying capacity and duration consistent with the timedsequence of work carrier travel in the remaining portions of theprocess.

Referring now to FIG. 2, the work carrier 14 comprises a generallyU-shaped frame including a pair of upright side members or legs 16,connected at their upper ends to a substantially horizontal cross member18. An elongated treating barrel comprised ofa pair of end members 22and a foraminous or perforate body member or panel 24 extends betweenand is rotatably supported at the center of its end members 22 bysuitable shafts affixed to the lower ends of the legs 16. The body panel24 of the treating barrel, as best seen in FIGS. 2, 5 and 6, is formedwith an elongated slot-like opening 26 extending longitudinally thereofand substantially parallel to the axis of rotation or oscillation of thebarrel providing access to the interior of the barrel. The body paneland two end members define a substantially cylindrical treating zone inwhich bulk quantities of workpieces are adapted to be disposed during atreating operation.

As best seen in FIGS. 2, 5 and 6, the body panel 24 i is formed with aninwardly converging section disposed diametrically opposite to theopening 26 defining therewith a tumbling rib 28 which imparts a tumblingor cascading action to a mass of workpieces, indicated at 30 in FIG. 6,in response to an oscillation of the treating barrel. The tumbling rib28 may vary in configuration so long as a satisfactory tumbling actionis imparted to the workpieces which is sufficient to release anyentrapped liquid therein and to expose fresh surface areas for contactwith the gas or air being discharged into the interior of the barrel. Inaccordance with a preferred construction of the treating barrel, theslot-like opening 26 extends for the entire length of the body panelfrom one end member to the other end member and is of a circumferentialwidth less than about l/6 of the circumference of the barrel and forbest results, from about 1/10 to about 1/20 of the circumferentiallength of the barrel. The tumbling rib 28 is preferably disposeddiametrically opposite to the opening and is of a generallytriangular-shaped cross section as defined by two flat faces whichproject into the interior treatingzone at an angularity ranging fromabout 10 to about with respect to a tangent to the body member at thepoint of intersection of the tumbling rib therewith. The entire area ofthe body panel 24 is of a foraminous structure as provided by aplurality of perforations generally indicated at 31 in FIG. 2.

The barrel itself is comprised of a suitable high strength materialwhich is resistant to and compatible with the acidic and alkalinetreating solutions into which the barrel is adapted to be immersedduring the course of its transfer through the various treatingsolutions. The material also is preferably of an electricallynonconductive type to enable use of the barrel in electroplating andother electrochemical treating processes and in which event a pair ofdangler electrodes 32, as bestshown in FIG. 2, are employed which extendinwardly through the tubular shaft and through the centers of the endmembers 22 and are adapted to be disposed in electrical contact with theworkpieces therein. A suitable cable (not shown) is connected to each ofthe dangler contacts and is adapted to be electrically connected to abus bar at such stations at which an electroplating or electrochemicaltreatment is to be performed on the workpieces. Particularlysatisfactory results are obtained with treating barrels comprised ofplastic materials such as nylon, polymethylmethacrylate, polyethylene,polypropylene and phenol formaldehyde resins.

A controlled oscillation of the treating barrel about a centrallongitudinally extending axis from a first position, such as shown insolid lines in FIG. 5, to a second position as schematically illustratedin FIG. 6, is conveniently achieved by a gear train comprised of adriven gear 34 affixed to a shaft 36 rotatably supported in a guideblock 38 affixed to and projecting laterally and outwardly of a leg 16of the work carrier as best seen in FIG. 2. A driven gear 40 is affixedto the inner end of the shaft 36 and is disposed in constant meshingrelationship with an idler gear 42, which in turn is disposed inconstant meshing relationship with a ring gear 44 secured to orintegrally formed on one of the end members 22. The driven gear 34 isadapted to be disposed in meshing relationship with a suitable drivegear when the work carrier is located at a work station in a manner andfor the purposes subsequently to be described.

The drying apparatus such as located at station 13 of FIG. 1 iscomprised, as best seen in FIGS. 3-5, of a pair of base beams 46defining a platform on which the framework of the apparatus is affixed.A return duct 48 of a generally rectangular-shape cross section isaffixed to the upper edges and extends longitudinally of the base beams46. The left-hand end of the return duct 48, as best seen in FIG. 4, isconnected to an angularly shaped transition section 50 which is of aprogressively increasing cross sectional area on moving toward the leftand is disposed with its output end connected to the lower side of aplenum chamber 52. Entry into the plenum chamber 52 from the transitionsection 50 is achieved through a venturi-shaped duct section 54 which isof a circular cross sectional configuration having its outlet enddisposed in communication with the inlet side of a squirrel-cage typecentrifugal blower 56 affixed to the end of a drive shaft 58. .The driveshaft 58, as best seen in FIGS. 3 and 4, is rotatably supported in ahousing 60 and a drive pulley 62 is affixed to the projecting outer endthereof. A motor 64 is mounted on a pad 66 and is provided with a pulley68 on the output shaft thereof, around which a drive belt 78 is trainedwhich drivingly engages the pulley 62 for effecting a rotation of thecentrifugal blower. Accordingly, the transition section 50 and theventuri-shaped duct section 54 are placed under a reduced pressurewhereby air or gas flows toward the left inthe direction of the arrowsas shown in FIG. 4 and into the centrifu gal blower 56, whereafter thegas or air is discharged upwardly and out of the upper section of theplenum chamber 52 into a heat exchanger 72 affixed to the dis chargeside thereof.

The heat exchanger 72, as best seen in FIG. 4, comprises a plurality ofheat transfer tubes 74 which are connected to a header conduit 76 at oneside and a return conduit 78 (FIG. 3) on the opposite side, throughwhich a continuous supply of a heat transfer fluid, such as steam, iscirculated, effecting therewith a controlled heating of the air or gaspassing therethrough. In the use of the apparatus as a dryer, thequantity and temperature of the heat transfer fluid passing through theheat transfer tubes is controlled so that the air discharged from theheat exchanger is of a preselected temperature andhumidity level toprovide optimum efficiency and economy in the drying cycle. The controlof the temperature of the air can readily be achieved by using, atemperature probe 80, as shown in FIG. 4, which is mounted at thedischarge side of the heat exchanger and is connected through suitablecircuitry to the central control panel 82 of the apparatus. The centralcontrol circuit is in turn effective through the use of a flow controlvalve of the types well known in the art to regulate the quantity ofheat transfer fluid passing through the heat exchanger and acorresponding control of the temperature of the air dischargedtherefrom.

The gas or air discharged from the outlet side of the heat exchanger 72enters a pair of longitudinally extending supply ducts 84 which. extendin spaced substantially Parallel relationship above the returnduct 48.The inlet ends of the supply ducts 84 are connected by a V-shaped bafflemember 86 which effects a division of the discharged heated gas into twoseparate and substantially equal streams in accordance with the arrowsas shown in FIG. 3. v

The return duct 48 and supplyducts 84 are disposed in communication withthe dimensional upwardly opening rectangular chamber 88, into which thework carriers are adapted to be lowered for the performance of atreating operation on the workpieces carried thereby. The chamber 88 is'comprised of a pair of side panels 90a, 98b; a pair of end panels 92a,92b and a bottom panel 94, which are securely fastened to each other andto the base beams and return ducts 48 therebelow. Side panel 900 isformed with a longitudinally extending discharge port 96a disposed incommunication with one of the supply ducts 84, as shown in FIG. 5, whileside panel 90b is similarly provided with a longitudinally extendingdischarge port 96b disposed in communication with the other supply duct84. The edges of the discharge ports 96a, 96b are lined with angle ironbrackets 98, as best interior of a three seen in FIGS. 3 and 5, to theprojecting leg portions of which resilient sealing strips 108 areaffixed. The angle iron brackets 98 and sealing strips 108 along eachdischarge port define in combination a flexible discharge nozzle, theend of which is adapted to resiliently engage the periphery of thetreating barrel 20, as shown in FIG. 5, directing the air or gasdischarged therethrough in the form of a concentrated high velocitystream in impinging relationship against the periphery of the barrel andthrough the perforations therein, as well as through the slot-likeopening 26 and in impinging relationship against the workpiecescontained within theinterior of the barrel. The pressurized airdischarged from the discharge ports also serves to dislodge or blow outany liquid treating solution entrapped within the perforations of thebody panel of the treating barrel accelerating the draining of thetreating solution and the evaporation thereof from the surfaces of theworkpieces. In accordance with this arrangement, the discharge ports andthe sealing strips disposed therealong are of a length correspondingsubstantially to the distance between the inner surfaces of the endpanels of the treating barrel and the length of the elongated slot-likeopening 26 therein.

A continuous withdrawal of the gas or air discharged into the interiorof the treating barrel is achieved through an outlet port 102 formed inthe bottom panel 94 of the treating chamber, as may be best seen inFIGS. 3 and 5, which extends centrally and longitudinally thereof and isdisposed in communication with the return duct 48. The edges of theoutlet port 102 are similarly lined with angle iron brackets 104, to theinward projecting leg portions of which sealing strips 106 are affixedand project such that the edges thereof are disposed in close proximityto or in resilient engaging contact against the periphery of thetreating barrel.

The negative pressure present in the return duct coupled with thepositive pressure present in the interior of the treating barrelprovides for a pressure gradient in ducing a continuous withdrawal ofgas or air from the interior of the barrel through the perforationsdisposed within the area .of the outlet port 102. Additional air alsoenters the outlet port which enters the barrel through the perforationsin the body panel disposed upwardly between the vupper sealing strips aswell as any leakage between the barrel periphery and the ends of thebarrel and the projecting ends of the resilient sealing strips 100 and106. Thewithdrawn air upon entering the return duct flows toward theleft in the direction of the arrows, as indicated in FIG. 4, and isagain drawn into the plenum by the centrifugal blower 56.

Since during a. drying operation,.a continuous build up in the moisturecontent of the recirculated air occurs, a suitable amount of make-up airis introduced into the recirculating duct system by means of a makeupport 188, as shown in FIG. 4, formed on the upper side of the transitionsection 58 over which an adjustably mounted closure member 110 ispositioned. By adjusting the position of the closure member relative tothe make-up port 108, a controlled amount of outside air can be drawninto the recirculatory duct system, whereby the humidity level of therecirculated air stream is maintained below the saturation point whileat the same time conserving the heat in the system.

In order to assure appropriate vertical and longitudinal alignment ofthe treating barrel relative to the discharge ports and outlet port,suitable supporting means are provided along the upper edges of thetreating chamber for removably engaging and retaining the work carrierin appropriate aligned and supported relationship. As will be noted inFIGS. 3 and 4, an angle iron reinforcing member 1 12 is affixed to theouter face of the panel 92b adjacent to the upper edge thereof, on whicha U-shaped saddle 114 is securely fastened and which in turn is adaptedto slidably and removably engage a lug 116 affixed to and projectinglaterally of one leg 16 of a work carrier as is best seen in FIGS. 2 and4.

In a similar manner, a saddle 118 is affixed to a support member 120mounted on the outer surface of the other end panel 92a, which similarlyis adapted to removably and slidably engage the guide block 38projecting outwardly of the other leg 16 of the work carrier frameworkas shown in FIG. 2. The saddles 114 and 118 are preferably of adivergent configuration at the upper ends thereof so as to faciitatealignment of the guide block 38 and lug 116 during the descendingmovement of the work carrier.

As will be further noted in FIGS. 3 and 4, a suitable drive mechanism isalso provided at the saddle 118 comprising a drive gear 122 connected tothe output shaft of a speed reducer 124, which is drivingly connected toa reversible fluid or electrical motor 126. The drive gear 122 isadapted to be disposed in driving meshing relationship with the drivengear 34 on the work carrier in accordance with the drive trainpreviously described in connection with FIG. 2.

The energization of the motor 126 and the corresponding oscillation ofthe treating barrel is controlled by the central control circuit of theapparatus contained within the control panel 82 affixed to the upperouter face of the plenum chamber 52. The control circuit incorporates adwell timer in accordance with known practice for effecting periodicenergization of the motor 126, whereby the treating barrel is oscillatedfrom a first position, as shown in solid lines in FIG. 5, in which theelongated opening 26 is disposed in communicative alignment with thedischarge port 96b to a secondposition, as shown in FIG. .6, in whichthe slotlike opening in the barrel is disposed in communicativealignment with the discharge port 96a. The angular movement of thetreating barrel is halted when it attains the appropriate alignedposition either by the incorporation of mechanical stops in the drivemechanism, by appropriate sensing devices such as limit switches forsensing the barrel position or, alternatively, by positive mechanicalstops 1280, 12812, as schematically shown in FIG. 6, which are affixedto the exterior face of one of the end panels and are adapted to becomemechanically engaged with an abutment 130 movably mounted on the leg 16of a work carrier.

In operation, a work carrier having a treating barrel filled withworkpieces is lowered automatically into the chamber 88 such that theguide block 38 and lug 116 on the carrier frame are disposed insupported relationship within the saddles 118 and 114, respectively. Airis continuously circulated through the duct system of the dryerapparatus by the centrifugal blower 56 while an appropriate quantity ofmake-up air enters the sytem through the make-up port 1108. Uponattaining the fully lowered position, the motor 126 is energized throughthe central control circuit, whereby the treating barrel is oscillatedfrom a normal position in which the opening is located in an uprightposition to either one of the positions typified by FIGS. 5 and 6. Uponattaining that position, a suitable dwell timer is energized in thecentral control circuit, whereby the treating barrel is retained in thatposition for a preselected time period to permit a concentrateddischarge of heated air through the slot-like opening in the barrelagainst the workpieces therein.

At the expiration of the dwell period, the motor 126 is again energizedwhereby the treating barrel is oscillated to the opposite position inwhich the opening is disposed in alignment with the other dischargeport. During the oscillatory movement of the barrel from one position tothe other position, a cascading of the workpieces over the tumbling ribof the barrel is effected, whereby any entrapped water or solution isdislodged and wherein when the barrel comes to rest, fresh surfaces ofworkpieces are exposed to the heated air discharged thereagainst. At thesame time rotation of the barrel effects a traverse of the peripherythereof with the concentrated jets of air being discharged from the twodischarge ducts, effecting a dislodgement of any entrapped water withinthe perforations of the body panel. The foregoing cycle is repeated fora preselected number of cycles, each including a dwell period of thetreating barrel at the extreme aligned positions. The specific number ofcycles and the dwell period at each position will vary depending uponthe size, configura tion and quantity of workpieces in the treatingbarrel, as well as the type, quantity and volatility characteristics ofthe liquid treating solution and the temperature and humidity level ofthe drying air or gas circulated therethrough. Normally a drying periodof less than about four minutes involving a dwell period at the alignedpositions of about ten seconds has been found satisfactory for providinga substantially complete drying of most workpieces incorporating aqueoustreating solutions thereon using saturated steam of a 6 to 12 psig asthe heat exchange fluid.

While it will be apparent that the invention herein disclosed is wellcalculated to achieve the benefits and advantages hereinabove set forth,it will be appreciated that the invention is susceptible tomodification, variation and change without departing from the spiritthereof.

What is claimed is:

1. An apparatus for treating workpieces in bulk while disposed in anelongated foraminous treating barrel formed with an opening extendinglongitudinally of the ends thereof comprising a framework defining anupwardly opening three-dimensional chamber for receiving a treatingbarrel adapted to be lowered therein, supporting means for removablysupporting a treating barrel in aligned position within said chamber,said chamber formed with a first discharge port and a second dischargeport extending longitudinally along the sides thereof and an outlet portin the lower portion thereof, drive means for oscillating a treatingbarrel through an angularity whereby the opening therein oscillates toand from a first position in communicative alignment with said firstport and a second position in alignment with said second port, ductmeans including a supply duct for supplying a gas to said first and saidsecond port for discharge against and into the barrel and the workpiecestherein and an exhaust duct connected to said outlet port forwithdrawing gas from said chamber, and control means for controlling theoscillatory movement of the barrel.

2. The apparatus as defined in claim 1, wherein said duct means includesa plenum connected in series with said exhaust duct and said supply ductfor recirculating at least a portion of the gas discharged into saidchamber through said first and said second discharge port.

3. The apparatus as defined in claim 1, wherein said duct means furtherincludes a heat exchanger for controlling the temperature of the gasdischarged into said chamber.

4. The apparatus as defined in claim 1, in which the gas comprises airand further including a plenum connected in series with said exhaustduct and said supply duct, blower means for recirculating the airwithdrawn from said chamber to said supply duct, and a third port formedin said duct means at the suction side of said blower means forintroducing make-up air into said duct means in admixture with the airrecirculated therethrough.

5. The apparatus as defined in claim 1, further including yieldablesealing means along the edges of said first port and said second portand projecting into said chamber for engaging the periphery of atreating barrel and directing the gas thereagainst and into the openingthereof.

6. The apparatus as defined in claim 1, further including yieldablesealing means along the edges of said outlet port and projecting intosaid chamber for engaging the periphery of a foraminous treating barreland enhancing the withdrawal of gas from the interior thereof.

7. The apparatus as defined in claim 1, wherein said control meansincludes timing means for maintaining a treating. barrel stationary fora preselected time period while disposed in said first position and insaid second position.

8. The apparatus as defined in claim 4, further including closure meansmovably disposed relative to said third port and adjustably positionableto control the amount of make-up air entering therethrough.

9. The apparatus as defined in claim 4, further including a heatexchanger in said duct means for heating the air to an elevatedtemperature in order to perform a drying operation on the workpieces inthe treating barrel.

10. The apparatus as defined in claim 9, further including closure meansmovably disposed relative to said third port and adjustably positionableto control the quantity of make-up air entering said duct means tomaintain the recirculated heated air at a humidity level below thesaturation point.

1. An apparatus for treating workpieces in bulk while disposed in anelongated foraminous treating barrel formed with an opening extendinglongitudinally of the ends thereof comprising a framework defining anupwardly opening three-dimensional chamber for receiving a treatingbarrel adapted to be lowered therein, supporting means for removablysupporting a treating barrel in aligned position within said chamber,said chamber formed with a first discharge port and a second dischargeport extending longitudinally along the sides thereof and an outlet portin the lower portion thereof, drive means for oscillating a treatingbarrel through an angularity whereby the opening therein oscillates toand from a first position in communicative alignment with said firstport and a second position in alignment with said second port, ductmeans including a supply duct for supplying a gas to said first and saidsecond port for discharge against and into the barrel and the workpiecestherein and an exhaust duct connected to said outlet port forwithdrawing gas from said chamber, and control means for controlling theoscillatory movement of the barrel.
 2. The apparatus as defined in claim1, wherein said duct means includes a plenum connected in series withsaid exhaust duct and said supply duct for recirculating at least aportion of the gas discharged into said chamber through said first andsaid second discharge port.
 3. The apparatus as defined in claim 1,wherein said duct means further includes a heat exchanger forcontrolling the temperature of the gas discharged into said chamber. 4.The apparatus as defined in claim 1, in which the gas comprises air andfurther including a plenum connected in series with said exhaust ductand said supply duct, blower means for recirculating the air withdrawnfrom said chamber to said supply duct, and a third port formed in saidduct means at the suction side of said blower means for introducingmake-up air into said duct means in admixture with the air recirculatedtherethrough.
 5. The apparatus as defined in claim 1, further includingyieldable sealing means along the edges of said first port and saidsecond port and projecting into said chamber for engaging the peripheryof a treating barrel and directing the gas thereagainst and into theopening thereof.
 6. The apparatus as defined in claim 1, furtherincluding yieldable sealing means along the edges of said outlet portand projecting into said chamber for engaging the periphery of aforaminous treating barrel and enhancing the withdrawal of gas from theinterior thereof.
 7. The apparatus as defined in claim 1, wherein saidcontrol means includes timing means for maintaining a treating barrelstationary for a preselected time period while disposed in said firstposition and in said second position.
 8. The apparatus as defined inclaim 4, further including closure means movably disposed relative tosaid third port and adjustably positionable to control the amount ofmake-up air entering therethrough.
 9. The apparatus as defined in claim4, further including a heat exchanger in said duct means for heating theair to an elevated temperature in order to perform a drying operation onthe workpieces in the treating barrel.
 10. The apparatus as defined inclaim 9, further including closure means movably disposed relative tosaid third port and adjustably positionable to control the quantity ofmake-up air entering said duct means to maintain the recirculated heatedair at a humidity level below the saturation point.